\(QS11_{12}^{(2)}\)

Description

Topological configuration of singularities: \(s,s,a,a;N,(0,2)SN\)

Phase Portrait

Topological Invariants

TCSP	Fin Sep	Inf Sep
\(11\)	\(4430\)	\(3211\)

Example

The quadratic differential system

\[\begin{cases} \dot{x} = ce \, x + x^{2} + 2 \, ch \, x \, y + (9/10 - 2 \, ch) \, y^{2} \\ \dot{y} = -5 \, x^{2} + y + 2 \, (101/20 + ch) \, x \, y + (-16/5 - 2 \, ch) \, y^{2} \end{cases}\]

has the following phase portrait done with P4. If you want, you may download the P4 file here.

The phase portrait appears in the following papers

With name \(BD42\) in {J. C. Artés}, Systems of class BD, {Preprint} (2026).